1. Field of the Invention
The present invention relates to a lamp unit for and to be mounted in an image projector to project images onto a screen or the like.
2. Description of the Related Art
Conventionally, an image projector is known such that, based on image data from a personal computer, a video camera and the like, images are formed by an image forming element, and the formed images are projected onto a screen or the like. This kind of image projector comprises a lamp unit to project light and an image projection unit to project the images formed by the image forming unit, using the light from the lamp unit.
The lamp unit has such structure that a lamp body is held in a lamp box. The lamp unit is attachably and detachably mounted on a body of the image projector so as to make it possible to replace the lamp body when the lamp body becomes unusable due to its degradation, life or the like. The lamp body comprises a lamp bulb supplied with electric power for emitting light, and a reflector fixed integrally to this lamp bulb for reflecting and collecting the light. The reflector is made of glass or the like from the viewpoint of heat resistance and efficiency of reflection, so that the reflector may possibly get broken if fixed by machine screws or the like. Accordingly, in order to be held in the lamp box, the reflector is pressed against a holding portion in the lamp box by a biasing member such as spring. Further, a cable (electric cable) is connected to the lamp body for supplying electric power to the lamp body. This cable has, at an end thereof, a connector which is connected to the body of the image projector when mounting the lamp unit in the body of the image projector.
Now, according to such lamp unit, the reflector is held in the lamp unit in a manner that the reflector within the lamp box is pressed against the lamp box by the biasing member. Accordingly, in the case where the cable is pulled at the time, e.g., of replacing the lamp, there is a possibility that the position of the lamp body may slip. If the position of the lamp body slips, the utilization efficiency of light from the lamp body decreases, and hence the images projected by the body of the image projector become dark. It is to be noted that even in the case where the reflector is made of metal, and is fixed by e.g. machine screws, there is a possibility that the position of the lamp body may slip if the cable is strongly pulled.
Thus, it is known to provide, in the lamp box of the lamp unit, a member for restricting the movement of the connector at the end of the cable, thereby preventing the cable from being pulled. In such lamp unit, the connector is slidably held by a rail provided in the lamp box, and can be connected to the body of the image projector by being slided along the rail. According to such lamp unit, the connector is restricted from moving in directions other than the direction along the rail, whereby the cable is prevented from being pulled more than necessarily.
Meanwhile, in a fixing device for fixing an cable (power supply cord) connected to a power supply unit of e.g. a television receiver, it is known: to provide a boss and a rib in a recessed groove; to form loop portions of the cable; to twist the intersecting portions of the loop portions; to place the loop portions of the cable around the outer circumference of the boss; and to insert the twisted intersecting portions of the loop portions of the cable into the space between the recessed groove and the rib. (Refer to e.g. Japanese Laid-open Patent Publication Sho 62-145898.)
Furthermore, in a cable drawing device in electronic equipment, it is known: to insert a cable into a hook provided at an inner surface of a housing; and to wind the cable around a boss from lower to upper position of the boss, the boss being placed to stand facing the hook. (Refer to e.g. Japanese Laid-open Utility Model Publication Sho 49-105855.)
However, according to the above-described conventional lamp unit, a member for restricting the movement of the connector is provided in a lamp box. Such member for restricting the movement of the connector is complex in structure, and causes cost increase. On the other hand, according to the two prior art references, the cable fixing structures are complex, and further require complex work to fix the cables. If the technologies disclosed in these references were applied to a lamp unit, the cost of the lamp unit would increase due to the complex cable fixing structures.